The present invention relates to a new structure for assembling a crutch having a easily adjusted length and grip height.
Crutches, fabricated from wood or metal (usually aluminum) tubes, have been used as an aid to assist injured or disabled individuals in standing or walking. While there are numerous design variations, a typical crutch has a xe2x80x9cYxe2x80x9d frame design with two upper members or bows which converge at a lower end where a central leg is formed or attached. The upper ends of the upper members extend vertically upward from the point of convergence and parallel to each other but spaced apart. An underarm support brace is attached across the upper ends of the bows. A horizontal hand grip is mounted between the upper members or bows at an arms length or slightly less than an arms length from the under arm brace.
In order to adjust the length of the wooden crutch to various height individuals the two bows of the crutch usually have one or two holes there through below where the upper members converge. This hole or holes receives a bolt which also passes through one of several horizontal holes along the length of the central leg or foot piece. Once a hole in the leg is selected to provide a crutch of the proper length the bolt is secured by applying a nut to the bolt. In a like manner, the hand grip is attached between the upper members at a proper height by placing a bolt or pin through the hand grip and one of several pairs of horizontal holes in the upper members.
When the crutch is constructed from metal tubes the central leg is usually telescoped within an upwardly extending tube with the adjustment accomplished by use of an internal spring biasing a pin through aligned holes in both the lower central tube and the upwardly extending tube.
A further alternative approach has the hand grip extending at a 90 degree angle from an upper bow.
With the crutches presently available, assembly of the crutch with proper dimensions, namely the length from lower tip to under arm support and hand grip location, for each different individual is difficult. Further, use of a screw driver and wrench or pliers is required to assemble, disassemble and reassemble the crutch. This procedure is time consuming and typically requires several attempts until the crutch is properly sized for the comfort and safety of each particular user. Also, because of limited length adjustability four or five different length crutch assemblies must be inventoried.
U.S. Pat. No. 4,917,126 to Ellmore shows a crutch comprising adjacent tubes secured together in a parallel manner using an upper and lower clamp. An upper tube is telescopically mounted in a first central tube with an underarm support attached to the top end. A lower tube telescopically mounted in a second central tube has a tip on its lower end. A handgrip is clamped to a central tube. The length (height) of the crutch is adjusted by extending the upper and lower tubes. The position of these tubes in the outer tubes is fixed by using a series of holes in the outer tube and a spring loaded plunger located within the inner tube. U.S. Pat. No. 4,846,203 to Tappel shows a similar construction with the exception that the centrally located outer tube is a single tube with two parallel holes.
U.S. Pat. No. 869,128 to Autenreith shows a crutch comprised of two parallel adjacently located tubes with a coupling attached to the lower end of the upper tube so as to receive the lower tube in a sliding manner. Extending from the bottom of the upper tube is a shaft which is captured in a sleeve mounted to the lower tube. The position of the shaft in relation to the upper and lower tubes is fixed using set screws.
U.S. Pat. No. 5,349,977 to Wood shows a crutch or walker with two parallel tubes with one tube having a roughened surface. The position of the two tubes in relationship to each other is fixed through the use of a pivoting piece.
U.S. Pat. No. 1,254,771 to Brown shows a portable bath house with adjustable length uprights comprising two parallel pieces. The lower piece has two collars through which the upper piece slides. Attached to the lower piece is a spring mounted bolt which slides in a hole in the first piece and sets in one of a series of holes on the second piece.
U.S. Pat. No. 1,888,972 to Chittim also shows two piece adjustable tent poles. The lower piece has an attached collar through which the second piece attaches. Also attached to the top of the first piece is a pivoting link The link includes a traverse pin which sets in a notch on the upper bar. This arrangement prevents the pole from shortening but does not prevent lengthening, thus making it an arrangement unsuitable for a crutch. U.S. Pat. No. 208,158 to Cushing and U.S. Pat. No. 35,963 to Warner and Palmer show other extendable tent poles.
There are numerous other patents, of which U.S. Pat. Nos. 5,139,040 and 5,752,535 are examples, that show crutches constructed of telescoping tubes with a series of holes and spring mounted pins for adjustment. In addition, there are numerous patents that use bolts and other more permanent assembly means.
U.S. Pat. Nos. 5,351,701, 5,402,811, 5,445,175 and 5,765,583 are representative of adjustable designs with two upper shafts and one lower shaft. These designs all appear to have the same type of fixturing for adjusting the extension of the lower leg, namely screws, bolts or spring pins.
The invention is directed to a crutch comprising two adjacently located, elongated, parallel shafts which can be moved in relationship to each other to form a vertical support of readily varied length. Each shaft has a series of parallel horizontal notches with the notches on each shaft positioned on contacting surfaces of the shafts. A pin inserted into parallel, adjacent notches on the two shafts in cooperation with two or more collars or caps fixes the relationship between the shafts which, in turn, defines the length of the vertical support. A similar concept can be used to lock a moveable centrally located shaft between two parallel outer shafts. These shafts are all held in their adjacent orientation by caps mounted on one end of each shaft with the second shaft slideable there through. This assemble provides a strong, adjustable length crutch from only two different pairs of bow lengths. Further, the upper and lower bow have the same design and are therefore interchangeable, significantly reducing inventory requirements.